Engine starter gearing



April 12, 1960 J. J. SABATINI 2,932,201

ENGINE STARTER GEARING Filed Dec. 26, 1957 -a Pamueaza zozizzzzzz G. j

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1N VEN TOR.

ATTORNEY ENGINE STARTER GEARING John J. S abatini, Horseh eads, N.Y .,.assignor to Bendix Aviation Corporation, Elmira Heights, N.Y., acorporation of Delaware The present invention relates to engine starter gearing and more particularly to that type which engages automatically upon energization'of the starting motor and maintains such engagement until a. successful start of the engine is secured. f

In the so called folohru starter drives of the type shown for instance in the patent to Buxton 2,609,695, issued September 9, 1952, a drive pinion is actuated by a control nut threaded on a hollow screw shaft which is connected to the motor shaft through a clutch which allows the drive pinion and the parts associated therewith to overrun when the engine starts. This overrunning action is sometimes objectionably noisy and it has been found by experiment that such noise can besubstantially reduced by yieldably clamping the screw shaft to the motor shaft to frictionally damp its relative motion. This may conveniently be accomplished by utilizing the expansive force of the drive spring, but when the thrust of said spring is transmitted through the overrunning clutch, the teeth of the clutch tend to wear comparatively rapidly.

It is an object of the present invention to provide a novel drive of the above type which is simple and durable in construction and effective and quiet in operation.

It is another object to provide such a device in which the movement of the overrunning parts is damped by a frictional connection to the motor shaft utilizing axial pressure of the drive spring, but the drive clutch is permitted to overrun freely and quietly. H

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

1 Fig. 1 is a side elevation partly broken away and in section of a preferred embodiment of the invention showing the parts in normal or idle position;

Fig. 2 is a similar view showing the parts in the positions assumed after the engine starts and overruns the starting motor while the pinion is still in mesh with the engine gear; and

Fig. 3 is a detail in perspective of the coupling and clutch members in disassembled relation.

In Fig. 1 of the drawing there is illustrated a power shaft 1 which may be the extended armature shaft of a motor not illustrated. A sleeve 2 comprising a driving head 3 is fixedly mounted on the shaft 1 as by means of a cross pin 4, and a coupling member 5 is slidably and rotatably mounted on said sleeve. An anchor ring 6 is non-rotatably mounted on the driving head 3, and connected to the coupling member 5 by means of a torsion and compression spring 7 having outturned ends 8, 9 seated in slots in the peripheries of said anchor ring and coupling member.

A screw shaft 11 is slidably journalled on the sleeve 2. A control nut 10 is threaded thereon and fixedly mounted in one end of a barrel 12. A pinion 13 is rigidly mounted in the opposite end of the barrel, and slidably joumalled on the power shaft 1 for movement into and out of mesh with an enginegear 14.

nited States Patent 2,932,201 Patented Apr. 12,1960

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The coupling member is formed as a ring with inwardly extending projections 15 (Fig. 3) which are slidably received in axial slots 16 in a clutch member ment ring to frictionally connect the screw shaft to the sleeve 2 and axle 1 to thereby damp its relative rotary movement. For this purpose a thrust sleeve 23 is seated in a counterbore in the clutch member 17 and the adjacent end of the screw shaft 11, bearing against a shoulder 24 in the screw shaft and at its other end against the projections 15 of the coupling member 5. The thrust sleeve 23 is of such length as to cause the spring 7 to be compressed sufficiently to secure the desired damping effect on the screw shaft 11.

In order to maintain initial contact of the overrunning clutch teeth 18, 19, a light compression spring 25 resting on the sleeve 2 is seated at one end in a counterbore in the clutch member 17 against shoulders 26, and at its other end bears against a thrust washer 27 which is seated against the driving head 3.

In operation, starting with the parts in the positions illustrated in Fig. 1, rotation of the power shaft 1 transmitted through the driving head 3, spring 7, coupling member 5 and clutch member 17 to the screw shaft 11 causes the control nut 10 to traverse the pinion 13 into mesh with the engine gear 14 by virtue of its connection through the barrel member 12. When the travel of the control nut 10 is arrested by the abutment ring 21, the screw shaft 11 is forced backward by screw-jack action, moving the clutch member 17 also to the left in Fig. l takingup the space 28 between the projections 15 of the coupling member and the bottoms of the slots 16. Further travel of the screw shaft and clutch member to the left compresses the drive spring 7 until such travel is arrested by the clutch member 17 engaging the thrust washer 27. Thereafter, rotation of the drive shaft is transmitted to the pinion yieldabl-y by torsion of the drive spring 7, the overrunning clutch teeth 18, 19 being wedged together by the axial thrust of the screw shaft 11.

When the engine starts, the acceleration of the pinion 13 by the engine gear 14 causes it to overrun, carrying with it the control nut 10. This permits the screw shaft to return to its idle position against the abutment ring 21 and then causes it to overrun the clutch member 17. Since at this time there is no pressure on the clutch member 17 except that of the light clutch spring 25, the clutch teeth 18, 19 overrun freely and quietly. The screw shaft 11, however, is pressed against the abutment ring 21 by the expansive force of the spring 7 as transmitted through the projections 15 of the coupling member 5 and the thrust ring 23. Consequently the relative rotation of the screw shaft 11 on sleeve 2 is frictionally damped, thus insuring quiet operation.

Although but one form of the invention has been shown and described in detail it will be understood that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive a power shaft, a driving head fixed thereon, a coupling member slidably and rotatably mounted on the shaft, an elastic compression and torsion member connecting said head and coupling member, a screw shaft slidably and rotatably mounted on the aesidi power shaft, 5 liitcii iiiefiiber slidably 55a rdt'a'tably mounted on the power shaft, having a splined connection with the coupling member and an overrunning clutch connection with the screw shaft, a pinion slidably journalled on the power shaft for movement into and out of mesh with a gear of an engine to be started, a control nut threaded on thescrew shaft, barrel member connecting the control nut to the pinion,..an'd means independent of the clutch member for frictionallynconnecting the screw shaft to the power shaft including a thrust member, directly connecting the coupling member and the screw shaft, and an abutment member fixed with respect to the power shaft,,limiting the travel of the screw shaft and the control nut in the direction of irieshing moye-.

ment, said abutment beingso positioned axially of the shaft as to maintain the elastic memberunder compression by means of the screw shaft, thrust member and coupling member. a a V 2. An engine starter drive as set forth in claim lineluding further a compression spring between thedriving head and the clutch member urging the clutch mem her into engagement with the screw shaft. u

3. An engine starter drive as set forth in claim 2 in which the iiieinber, the coupling member and the screw shaft are so formed and arranged as to transmit the pressure of the elastic torsion and compression member to the screw shaft when the parts are in idle position, while leaving the clutch member free to move out of engagement with the screw'shaft by compressing said spring.

4. An enginq starter drive as set forth in claim 3 in which the coupling member isin the form of a ring having inwardly: extending projections, and the clutch member is formed 'with'slots slidably receiving said projections, said thrust member being in the form of a sleeve slidably mounted on the power shaft, bearing at one end against said projections and at the other end against saidv screw shaft.

References Cited in the file of this patent U IT D sTATEs PATENTS 

